KSZ8862 Micrel Semiconductor, KSZ8862 Datasheet - Page 29

• Manufacturer Part Number: KSZ8862
• Description: 2-port Ethernet Switch With Non-pci Interface And Fiber Support
• Manufacturer: Micrel Semiconductor

Functional Overview: MAC and Switch
Address Lookup
The internal lookup table stores MAC addresses and their associated information. It contains a 1K entry unicast address
learning table plus switching information.
The KSZ8862M is guaranteed to learn 1K addresses and distinguishes itself from hash-based look-up tables, which
depending upon the operating environment and probabilities, may not guarantee the absolute number of addresses it can
learn.
Learning
The internal lookup engine updates its table with a new entry if the following conditions are met:
1. The received packet's Source Address (SA) does not exist in the lookup table.
2. The received packet is good without receiving errors; the packet size is legal length.
The lookup engine inserts the qualified SA into the table, along with the port number and time stamp. If the table is full,
then the last entry of the table is deleted to make room for the new entry.
Migration
The internal look-up engine also monitors whether a station has moved. If a station has moved, it updates the table
accordingly. Migration happens when the following conditions are met:
1. The received packet's SA is in the table but the associated source port information is different.
2. The received packet is good without receiving errors; the packet size is legal length.
The lookup engine updates the existing record in the table with the new source port information.
Aging
The look-up engine updates the time stamp information of a record whenever the corresponding SA appears. The time
stamp is used in the aging process. If a record is not updated for a period of time, the look-up engine removes the record
from the table. The look-up engine constantly performs the aging process and continuously removes aging records. The
aging period is about 200 seconds. This feature can be enabled or disabled through Global Register SGCR1 [10].
Micrel, Inc.
April 2007
29
KSZ8862-16/32MQL
M9999-040407-3.0